[petsc-dev] Problem with SLEPC Eigenvalue Problem Solver
Jose E. Roman
jroman at dsic.upv.es
Tue Oct 22 07:56:59 CDT 2013
El 22/10/2013, a las 14:39, Ricardo Marquez escribió:
> Hi, I'm trying to solve a vibration generalized eigenvalue problem like this:
>
> | K C | = lambda* | M 0 |
> | C^t 0 | | 0 0 |
>
> I have try a lot of convinations eigensolvers, KSP and PC, but I can't make that it works.
> I use the ST shift-and-invert to get the firsts 5 eigenvalues.
> If I use PC or ST_PC = LU or CHOLESKY, I get the zero pivot message error.
> If I use PC and ST_PC = NONE, the 5 eigenvalues that find the solver are exactly the same and equal to the shift value.
> If I use PC = jacobi or bjacobi, the eigenvalues get a very big value.
>
> Does anyone knows how this kind of problem solve?
>
> thanks!
> --
> Ricardo Márquez
If C has a relatively small number of columns, you may consider formulating the problem as a constrained eigenproblem
K x = lambda M x, with C^t x = 0
Try representing C as a Vec array and passing them to EPSSetDeflationSpace() before EPSSolve().
Jose
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